1. Field of the Invention
This invention relates to absorbent articles, as well as to an apparatus and method for producing absorbent articles. More particularly, the present invention provides absorbent cores made from two or more absorbent materials, wherein at least one of these absorbent materials is provided in one or more strips.
2. Description of Related Art
Absorbent articles for the absorption and retention of discharged bodily fluids (urine, blood, vaginal discharge, etc.) are well known in the prior art, and generally include an absorbent core having one or more absorbent materials therein. In the case of diapers, incontinence pads, sanitary napkins, pantiliners and the like, the absorbent core is generally disposed between a topsheet and a backsheet. The topsheet is fluid pervious, and allows discharged fluids to pass therethrough for absorption by the core. The backsheet is generally fluid impervious, and prevents absorbed fluids from escaping the absorbent article.
Various types of absorbent materials may be incorporated into the core of the article, particularly cellulosic fibers such as wood pulp. Recently, superabsorbent polymers also known as absorbent gelling materials (AGM's) have been developed which can be incorporated into absorbent cores for improved performance. AGM's are polymeric materials which are capable of absorbing large quantities of fluids to form hydrogels and which are further capable of retaining the absorbed fluids under moderate pressures. Typically, the AGM is incorporated along with one or more conventional fibrous materials, often in multi-layer configurations. For example, the absorbent core of an absorbent article may comprise one layer consisting solely of cellulosic fibers, and a second layer consisting of a uniform combination of cellulosic fibers and AGM particles.
Manufacturing multi-component absorbent cores can be difficult and expensive, and often requires two or more separate core-making apparatus. While various apparatus for overcoming this problem have been suggested, such as that disclosed in U.S. Pat. No. 5,447,677, it is often difficult to control the amount and location of AGM deposition in such apparatus. Since AGM's are significantly more expensive than more traditional fibrous materials, it is advantageous to insure that the amount and location of AGM is precisely controlled. Such control is difficult, however, with conventional air-laying apparatus.
Precise control of the amount and location of AGM within the core is desirable not only due to costs, but also for improved performance. While AGM's rapidly absorb many times their weight in fluids, they are subject to gel-blocking. Gel-blocking occurs when the surface of an AGM particle, film, or fiber rapidly swells with absorbed fluid and prevents fluid transmission to the interior of the particle, film or fiber. When this occurs, wetting of the interior takes place via a very slow diffusion process, and the absorbent article may fail well before the AGM has reached its fluid capacity.
Thus, there is a need for absorbent articles having a first absorbent material such as cellulosic fibers, and a second absorbent material, such as an AGM, wherein the second material is selectively provided in at least one strip within the first material, as well as an apparatus and method for producing such absorbent articles.